This invention relates to methods for controlling the spacing of a motor vehicle from an object in front of the vehicle, in which at least the present driving speed of the motor vehicle and the present spacing from an object in front of the motor vehicle are determined by sensor devices and a spacing-dependent required acceleration value is determined from the sensed variables, and to an arrangement for carrying out the method.
Improvements in the field of motor vehicle electronics have led to the situation in which electronic systems which relieve the vehicle driver of routine functions are gaining increasing importance. These electronic systems include, inter alia, a speed control system, which has been known for a long time, in which the driver can preselect a desired speed which is then maintained by the system.
Because of increasing volumes of traffic, it has become necessary to make such speed control additionally dependent on the current traffic situation since the driver would otherwise be compelled to intervene continually in the control of the vehicle speed.
In the publication "Abstandsregelung von Fahrzeugen mit Fuzzy Control" [spacing control of vehicles, using fuzzy control], Tagungsband der 3. Dortmunder Fuzzy Tage, Reihe Informatik Aktuell, Springer Verlag 1993, a fuzzy vehicle spacing controller is described which automatically maintains a predetermined required spacing of a vehicle from another motor vehicle travelling in front of the vehicle under various boundary conditions. The fuzzy spacing control described in the publication, which includes a three-stage fuzzy controller, uses simple min/max operators and the center of gravity method for defuzzification following each stage. Instead of a fixedly defined required spacing, a variable required spacing is determined in the first fuzzy controller which depends on the driver type and the weather, in addition to the current vehicle speed. The driver type and the weather are standardized parameters having a predetermined value range which is determined by an external sensing mechanism, but an arrangement for determination of a driver type is not described in the publication.
The three input data, i.e., driver type, weather, and vehicle speed, are fuzzified and projected onto the required spacing by two control matrices. In the second fuzzy controller, the current spacing supplied by the sensing mechanism is compared to a required spacing determined in the first fuzzy controller and the acceleration required to maintain the desired spacing, which is dependent on the driver type, is determined. The desired vehicle speed is entered directly by the driver and, in the third fuzzy controller, this leads to a threshold value determination as a function of the predetermined desired speed. Subsequently, as a function of the required acceleration and the actual acceleration, the pedal position of a combined accelerator and braking pedal is determined.